ON RELIABILITY EVALUATION OF TEST RESULTS FOR PHYSICAL PROPERTIES OF CONSTRUCTION MATERIALS

Analysis of regulatory documents for the last 40 years has shown a lot of differences in methodology and results of calculations on determination of physical properties and reliability indices of construction materials and structure elements. A variety of the recommended regulatory documents indicates significant uncertainty in principles used for selection of reliability levels while determining strength properties of concrete which depend on probability characteristics. A substantial variety of methods for distribution of physical property values of construction materials and products rather often leads to necessary usage of empiric characteristics of statistic physical property coefficients.

Methodology for evaluation of confidence limits for dispersion in accordance with chi-square criterion using small select query which was described by K. A. Brownlee under the editorship of Academician A. N. Kolmogorov has been practically forgotten for the period of the last 60 years. For this reason presently applied methodology for statistical evaluation of calculation value reliability for concrete strength can be unsatisfactory especially in the case of small number of evaluations (less than 50). Taking into account the possible departure from normality in probability density for parameter realization a general level of statistical changeability account should be taken as not less than 0,98.

The paper proposes a new methodology for determination of minimum number of measurements required for construction material or a product reliability of its evaluation in accordance with the recommendation of K. A. Brownlee which was edited by A. N. Kolmogorov.

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